Fermis

Fermis is a proposed unit of measurement for extremely small time intervals, equivalent to one quadrillionth of a second (10^(-15) seconds). This is the same scale as the femtosecond, a standard unit in the International System of Units (SI). The term "Fermis" is not officially recognized and appears to be an informal or historical name, possibly coined to honor the physicist Enrico Fermi, a key figure in nuclear and particle physics.

The timescale of fermis or femtoseconds is crucial in the study of ultrafast phenomena. It represents the timescale on which atomic and molecular events occur. For example, the vibrations of atoms within a molecule and the breaking or forming of chemical bonds happen within hundreds of femtoseconds. Observing these processes requires sophisticated equipment like femtosecond lasers.

The name draws a parallel to the Fermi unit used for length, which is also named after Enrico Fermi. One fermi is equal to one femtometer (10^(-15) meters), a unit used to measure nuclear distances. While the fermi (length) is an accepted, though less common, unit, the use of "Fermis" for time remains largely anecdotal within scientific literature. In contemporary practice, the SI unit femtosecond is universally preferred for clarity and standardization when discussing these incredibly brief time spans.